The correct option is
B a promise or undertaking to pay a certain sum of money.
Promissory note contains
B. a promise or undertaking to pay a certain sum of money.
As we know as per defination a promissory note is a written promise to pay a debt.It is a financial instrument in which one party (maker or issuer) promises in writing to pay a determined sum of money to the other (the payee) ether at a fixed determinable future time or on demand of the payee subject to specific terms.